The present invention relates to the field of orthodontic appliances, and more particularly to an improved, removable and adjustable transpalatal arch wire capable of accurately transmitting correctional intrusion forces to a pair of brackets mounted on opposing molars.
In the straightening of teeth by an orthodontist, a commonly encountered malocclusion is a skeletal open bite, which is caused by misaligned upper and lower jaws. A skeletal open bite is characterized in a person whose upper and lower front and side teeth do not close together, but only the back two teeth (the first and second molars) on the top and bottom jaws come together and touch, making it difficult for the person to chew food or to close their mouth.
Orthodontists have heretofore used vertical elastics from the upper front teeth to the lower front teeth in an attempt to close the front and side teeth together vertically. Unfortunately, the front and side teeth usually relapse to the pretreatment condition after the elastics are removed. Moreover, long-term heavy elastic wear in these types of cases has been associated with root resorption (root shortening), thereby causing damage to the teeth. Another approach employed jointly by orthodontists and oral surgeons is for the orthodontist to straighten the teeth first and subsequently the oral surgeon performs jaw surgery to properly align the jaws. This, however, is an extremely expensive treatment, has the inherent risk of postoperative paresthesia (numbness), and more importantly has the added risk of possible death when the patient is put to sleep for surgery.
Palatal arch wires currently utilized can be used to connect the upper back first molars together and create movement about the teeth, but do not allow simultaneous intrusive forces to be applied to said molars. For example, because the molars are connected across the arch, bending the arch wire to place an intrusive force on one of the connected molars simultaneously places an extrusive force on the other molar due to Newton's third law—for every for action there is an equal and opposite reaction. Further, the amount of intrusion possible with such arch wires is no more than 0.5-1.0 mm at most. For treatment of a skeletal open bite, back molar intrusion requires an average of 3-7 mm, depending on the severity of the open bite.
Improvements to palatal arch wires have included the addition of a U-shaped locking bar to prevent dislodgement from the brackets, thereby allowing it to also be attached to the second molars. Such locking bars also defined an arm or hook for receiving an elastic for applying forces to other teeth. Because all the upper teeth lie in a horizontal line, connecting the elastic from the palatal arch wire to other upper teeth only allows horizontal forces to be applied to the palatal arch wire connected teeth, which will not aid in correcting a skeletal open bite. The same elastic force, if connected from the palatal arch wire hook to the lower teeth, would actually create an extrusive force on the palatal arch wire connected teeth, which would make the open bite worse. Another problem with the locking bar is that it must be bent away from the tooth to allow bracket insertion, then bent back toward the tooth for locking to prevent dislodgement. This same action must occur every time the palatal arch wire is removed for adjustment, predisposing the locking bar to fatigue failure and breakage because of continued adjustment.
Because of the proximity of the locking bar/hook to the bracket connected to the palatal arch wire, a force exerted via an elastic could only be applied close to the molar to which it is attached. Since a skeletal open bite is characterized by the back first and second molars touching, the best location for an intrusive force is between these teeth anteroposteriorly. Such a solution is not yet in the art.
What has been introduced is a simpler insertion of the palatal arch wire into the bracket by employing a round horizontal wire. In order to provide for mediolateral control of tooth movement, or torque, a vertically oriented bar was attached to the round insertion wire on both sides of the interconnecting arch wire. However, this is not always ideal. For example, in patients with canted occlusal planes, where the teeth are lower on one side of the mouth than the other, intrusion is desired on one side only. In this case, the palatal arch wire should only have a vertically oriented bar on the side of the mouth where intrusion is desired. The opposite side should have no vertically oriented bar so that the wire can simply rotate inside the bracket tube without applying torque.
Recently, orthodontic temporary anchorage devices have been used to improve tooth movement. An orthodontic temporary anchorage device is a device that is temporarily fixed to bone structure for the specific purpose of enhancing and providing sufficient orthodontic anchorage either by supporting the teeth of the reactive unit or by obviating the need for the reactive unit altogether, and which is subsequently removed after use. In orthodontics, a temporary anchorage device refers to all variations of implants, screws, pins and plates placed specifically for the purpose of providing orthodontic anchorage and can be removed upon completion of biomechanical therapy. Orthodontic temporary anchorage devices are useful when applied in the correction of dental discrepancies, which include anteroposterior tooth movements, molar uprighting, and intrusion/extrusion of single and multiple teeth. Orthodontic temporary anchorage devices can also be useful in the correction of oral skeletal discrepancies, as in the case of a skeletal open bite. There exists a need however for a mechanism of connecting the teeth, or orthodontic appliances thereon, to the orthodontic temporary anchorage devices.